Abstract: On February 17, 1988, workers for the Prillaman and Pace Company encountered rock while digging a trench for an 8 in. sewer line. They decided to break up the rock to finish the trench, and drilled nine 2 ft holes with an air-operated hammer. Two 1/2 in. by 8 in. sticks of explosive (40 percent nitroglycerin) were placed in each hole, covered with 4 ft of dirt, and detonated at 3:40 p.m. that same day. At 8:00 a.m. on February 18, 1988, a backhoe operator uncovered the holes and determined that the rock had not been split apart. He sent Employee #1, a 19-year-old laborer, into the trench to drill more holes. When Employee #1 started to drill, an unexploded stick of dynamite under his feet detonated. Employee #1 sustained injuries to his legs, arms, and face, and was hospitalized. Subsequent investigation revealed that three more sticks had never exploded.